在C++中重载的指针问题？

class MyPointer {
public:
    MyPointer(int* ptr) : ptr_(ptr) {}
    int& operator*() {
        return *ptr_;
    }
    MyPointer& operator++() {
        ptr_++;
        return *this;
    }
private:
    int* ptr_;
};

int arr[3] = {1, 2, 3};
MyPointer ptr(arr);
std::cout << *ptr<< std::endl; // 输出1
++ptr;
std::cout << *ptr<< std::endl; // 输出2